1. Field of the Invention
The present invention relates to a piezoelectric film comprising a piezoelectric layer and a method of manufacturing the piezoelectric film. The present invention further relates to an ink jet head comprising the piezoelectric film and a method of forming an image by the head, to an angular velocity sensor comprising the piezoelectric film and a method of measuring an angular velocity by the sensor, and to a piezoelectric generating element comprising the piezoelectric film and a method of generating electric power using the element.
2. Description of the Related Art
Perovskite composite oxide [(Bi, Na)1-βBaβ]TiO3 (hereinafter, referred to as “NBT-BT”) has been recently researched and developed as a non-lead (lead-free) ferroelectric material.
Japanese Patent Publication No. Hei 4-60073B and T. Takenaka et al., Japanese Journal of Applied Physics, Vol. 30, No. 9B, (1991), pp. 2236-2239 disclose that a NBT-BT layer has high piezoelectric performance when the NBT-BT layer has a composition around the Morphotropic Phase Boundary (hereinafter, referred to as “MPB”) having a barium molar ratio β (=[Ba/(Bi+Na+Ba)]) of 3-15%.
Japanese Patent Publication No. 4140796B and E. V. Ramana et al., Solid State Sciences, Vol. 12, (2010), pp. 956-962 disclose (1-α)(Bi,Na,Ba)TiO3-αBiFeO3 where perovskite composite oxide NBT-BT is combined with perovskite oxide BiFeO3. The piezoelectric performance of the (1-α)(Bi,Na,Ba)TiO3-αBiFeO3 is maintained even at a solder reflow temperature of 180 degrees Celsius.
The (1-α) (Bi, Na, Ba) TiO3-αBiFeO3 has also been expected as a non-lead ferroelectric material capable of being used instead of PZT. However, the (1-α) (Bi, Na, Ba) TiO3-αBiFeO3 has lower piezoelectric performance than the PZT.
A ferroelectric material containing (Bi, Na, Ba) TiO3 or BiFeO3 has high dielectric loss. When the dielectric loss is high, the ferroelectric performance and the piezoelectric performance are deteriorated significantly.